This invention relates to an easy-opening end container wall and more particularly, to an improved pull tab of the type attachable to a removable section in the container wall.
There are several general types of easy-opening end closures for containers all of which use pull tabs to initiate severance of a removable portion therefrom. In one type of closure, a relatively small tear-out section is removed to permit pouring of liquid contents, such as beverages, from the container. In another type, a central panel, comprising most of the easy-opening end closure, is removed to permit removal of solid and semi-solid type contents, such as processed foods. In this latter type of closure, the pull tab is normally positioned with its nose located over or adjacent to a generally circumferential score line and with its lifting portion projecting inwardly towards the center of the closure. This type of pull tab arrangement can cause problems by it free end or lifting portion projecting upwardly from the closure during processing steps.
In preparing processed foods, for example, high pressure is experienced within the container as it is subjected to a sterilization treatment subsequent to the canning process. The high pressure tends to cause the central panel of the easy-open end closure to bulge or dome outwardly. This outward doming of the central panel can cause the free end or lifting portion of the pull tab to project upwardly, often beyond the can chime, which may result in accidental opening of the container by the free end catching or snagging and consequently being torn off. Holc et al U.S. Pat. No. 3,780,902 teach that this problem may be solved by providing means in the central panel for releasably holding the opening tab substantially flat against the central panel when the central panel bulges outwardly due to internal pressure of the container. However, this solution requires additional forming in the central panel to provide protuberances which releasably engage the pull ring of the opening tab.
An improved pull tab is provided in which, without requiring additional forming in the central panel, the lifting portion of pull ring thereof will remain substantially flat against the central panel even though the panel is domed due to internal pressure.